1. Field of the Invention
This invention relates to apparatuses and methods for inspecting the interior of conduits and pipes, particularly pipelines, such as sewers, air ventilation ducts, or liquid or gas transport pipelines, and locating defects such as corrosion, joint separations, cracks, depressions, or crushes in same, as well as roots, debris, blockages, and the like. More specifically, this invention relates to viewing devices and methods for movably scanning the interior of pipes or pipelines and to the collection of data for analysis and interpretation of the results of such scanning to evaluate the condition of the pipelines and the location of any defects in the pipelines.
2. Description of Relevant Art
As used herein, the term “pipeline” or “pipelines” shall be understood to include conduits, pipes, and ducts as well as pipelines and other such lines for transporting storm or sanitary sewage, air, liquids, gases or slurries. Known systems for inspecting pipelines typically comprise a television camera or a video camera mounted on a self-propelled electric tractor or on a sled pushed by a semi-rigid cable along the pipe from an open end of the pipe. Lights are attached to illuminate the pipeline interior. Both the lights and the camera are powered by the cable. An image of the pipeline is captured by the camera and recorded by a VCR (video cassette recorder) for viewing. The standard mode of operation employs pan, tilt and zoom capabilities by the camera. A forward looking view down the center of the pipeline is typically displayed and recorded, unless the operator stops to take a closer look—to pan, tilt and zoom—at a particular area of the pipeline. The taking of a closer look is dependent on the operator's subjective judgment during the inspection. If the operator, for whatever reason, does not visually identify an area of potential interest or concern (cracks, roots, etc.) in the forward looking view, the opportunity to stop, pan, and tilt to get more detailed information is lost. If a subsequent view of the video tape alerts another viewer to a potential problem area, detailed information can only be acquired by reinspecting the pipeline.
Common problems with known commercial systems have included inability to accurately gauge the location of a detected defect, insufficient lighting to identify a defect, distortion of image, inadvertent missing of defects, uneven quality and subjective defect classification, and requirement for burdensome review of volumes of video tapes after the inspection in an effort to decipher the video tapes and to distinguish defects from shadows. Most typically, use of known commercial systems can result in oversight of critical cracks and other defects in the pipeline.
Canadian patent application no. 2,216,800 of Core Corp. generally discloses or suggests a device using a beam of light reflected off of a rotating mirror said to provide a 360 degree round image of a pipeline. However, this device does not appear to include a digital forward view of the pipeline.
There continues to be a need for improved methods and apparatuses for fast, accurate and economical inspection of pipelines and evaluation of data associated with same.